Changes in dermatomal somatosensory evoked potentials according to stimulation intensity and severity of carpal tunnel syndrome

Objective: To investigate the change of latency of cervical dermatomal somatosensory evoked potential (DSEP) according to stimulation intensity (SI) and severity of carpal tunnel syndrome (CTS). Methods: Stimulation sites were the C6, C7, and C8 dermatomal areas. Two stimulation intensities 1.5×sensory threshold (ST) and 2.5×ST were used on both normal and CTS patients. Results: In moderate CTS, the latencies of C6 and C7 DSEP during 1.5×ST SI and those of C7 DSEP during 2.5×ST SI were significantly delayed compared with the values of normal subjects. Significant correlation between the latency of C7 DSEP of 2.5×ST stimulation and the median sensory nerve conduction velocity was observed. Conclusion: We suggest that these data can aid in the diagnosis of cervical sensory radiculopathy using low stimulation intensity and of those who have cervical sensory radiculopathy combined with CTS patients.